/* $Id$ */

/** @file thread_pthread.cpp POSIX pthread implementation of Threads. */

#include "stdafx.h"

#include "thread.h"

#include "debug.h"

#include "core/alloc_func.hpp"

#include <stdlib.h>

#include <pthread.h>

#include <semaphore.h>

#include <unistd.h>

/**

 * POSIX pthread version for ThreadObject.

 */

class ThreadObject_pthread : public ThreadObject {

private:

	pthread_t m_thr;             ///< System thread identifier.

	OTTDThreadFunc m_proc;       ///< External thread procedure.

	void     *m_param;           ///< Parameter for the external thread procedure.

	bool      m_attached;        ///< True if the ThreadObject was attached to an existing thread.

	sem_t     m_sem_start;       ///< Here the new thread waits before it starts.

	sem_t     m_sem_stop;        ///< Here the other thread can wait for this thread to end.

public:

	/**

	 * Create a pthread and start it, calling proc(param).

	 */

	ThreadObject_pthread(OTTDThreadFunc proc, void *param) :

		m_thr(0),

		m_proc(proc),

		m_param(param),

		m_attached(false)

	{

		sem_init(&m_sem_start, 0, 0);

		sem_init(&m_sem_stop, 0, 0);

		pthread_create(&m_thr, NULL, &stThreadProc, this);

		sem_post(&m_sem_start);

	}

	/**

	 * Create a pthread and attach current thread to it.

	 */

	ThreadObject_pthread() :

		m_thr(0),

		m_proc(NULL),

		m_param(0),

		m_attached(true)

	{

		sem_init(&m_sem_start, 0, 0);

		sem_init(&m_sem_stop, 0, 0);

		m_thr = pthread_self();

	}

	/* virtual */ ~ThreadObject_pthread()

	{

		sem_destroy(&m_sem_stop);

		sem_destroy(&m_sem_start);

	};

	/* virtual */ bool IsRunning()

	{

		return m_thr != 0;

	}

	/* virtual */ bool WaitForStop()

	{

		/* You can't wait on yourself */

		assert(!IsCurrent());

		/* If the thread is not running, waiting is over */

		if (!IsRunning()) return true;

		int ret = sem_wait(&m_sem_stop);

		if (ret == 0) {

			/* We have passed semaphore so increment it again */

			sem_post(&m_sem_stop);

			return true;

		}

		return false;

	}

	/* virtual */ bool Exit()

	{

		/* You can only exit yourself */

		assert(IsCurrent());

		/* If the thread is not running, we are already closed */

		if (!IsRunning()) return false;

		/* For now we terminate by throwing an error, gives much cleaner cleanup */

		throw 0;

	}

	/* virtual */ void *Join()

	{

		/* You cannot join yourself */

		assert(!IsCurrent());

		void *ret;

		pthread_join(m_thr, &ret);

		m_thr = 0;

		return ret;

	}

	/* virtual */ bool IsCurrent()

	{

		return pthread_self() == m_thr;

	}

	/* virtual */ uint GetId()

	{

		return (uint)m_thr;

	}

private:

	/**

	 * On thread creation, this function is called, which calls the real startup

	 *  function. This to get back into the correct instance again.

	 */

	static void *stThreadProc(void *thr)

	{

		return ((ThreadObject_pthread *)thr)->ThreadProc();

	}

	/**

	 * A new thread is created, and this function is called. Call the custom

	 *  function of the creator of the thread.

	 */

	void *ThreadProc()

	{

		/* The new thread stops here so the calling thread can complete pthread_create() call */

		sem_wait(&m_sem_start);

		/* Call the proc of the creator to continue this thread */

		try {

			m_proc(m_param);

		} catch (...) {

		}

		/* Notify threads waiting for our completion */

		sem_post(&m_sem_stop);

		return NULL;

	}

};

/* static */ ThreadObject *ThreadObject::New(OTTDThreadFunc proc, void *param)

{

	return new ThreadObject_pthread(proc, param);

}

/* static */ ThreadObject *ThreadObject::AttachCurrent()

{

	return new ThreadObject_pthread();

}

/* static */ uint ThreadObject::CurrentId()

{

	return (uint)pthread_self();

}

/**

 * POSIX pthread version of ThreadSemaphore.

 */

class ThreadSemaphore_pthread : public ThreadSemaphore {

private:

	sem_t m_sem;

public:

	ThreadSemaphore_pthread()

	{

		sem_init(&m_sem, 0, 0);

	}

	/* virtual */ ~ThreadSemaphore_pthread()

	{

		sem_destroy(&m_sem);

	}

	/* virtual */ void Set()

	{

		int val = 0;

		if (sem_getvalue(&m_sem, &val) == 0 && val == 0) sem_post(&m_sem);

	}

	/* virtual */ void Wait()

	{

		sem_wait(&m_sem);

	}

};

/* static */ ThreadSemaphore *ThreadSemaphore::New()

{

	return new ThreadSemaphore_pthread();

}